Ductility and deformability of fibre composites strengthened reinforced concrete beams

摘要

The brittle failure mode seen in many Fibre Reinforced Polymer (FRP) composites strengthened concrete elements is due to a lack of system ductility, and is a prime concern to the structural engineers. This paper discusses the distinction between deformability and ductility of reinforced concrete (RC) beams strengthened by externally bonded FRP composites. High deformability index does not necessarily lead to good ductility, as very brittle failure modes of such beams have been observed in the experimental studies. An energy-based method was found to be more suitable for quantifying ductility levels of FRP strengthened RC members. It was found that acceptable degree of ductility for FRP strengthened concrete flexural elements could be achieved if the cross sectional area and the properties of the composites were designed at an optimised level.